How to Calculate Heart Rate from Wiggers Diagram

Wiggers Diagram Heart Rate Calculator

Seconds (s) Milliseconds (ms)

Calculated Heart Rate:

function calculateWiggersHR() { var duration = parseFloat(document.getElementById('cycleDuration').value); var unit = document.getElementById('timeUnit').value; var resultDiv = document.getElementById('wiggersResult'); var outputDiv = document.getElementById('hrOutput'); var categoryDiv = document.getElementById('hrCategory'); if (isNaN(duration) || duration <= 0) { alert("Please enter a valid positive cycle duration."); return; } var heartRate; if (unit === "seconds") { heartRate = 60 / duration; } else { // Milliseconds conversion heartRate = 60000 / duration; } outputDiv.innerHTML = heartRate.toFixed(1) + " BPM"; var category = ""; if (heartRate 100) { category = "Category: Tachycardia (Faster than typical resting)"; } else { category = "Category: Normal Resting Heart Rate"; } categoryDiv.innerHTML = category; resultDiv.style.display = "block"; }

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Understanding the Wiggers Diagram and Heart Rate

The Wiggers Diagram is a fundamental tool in cardiovascular physiology. It maps the events of a single cardiac cycle by showing synchronized changes in aortic pressure, ventricular pressure, atrial pressure, ventricular volume, the electrocardiogram (ECG), and heart sounds (phonocardiogram).

How to Extract Heart Rate from the Diagram

To calculate the heart rate from a Wiggers diagram, you must first determine the Duration of One Cardiac Cycle. This is typically found on the X-axis (the horizontal time axis). You can measure this duration using several markers:

• R-R Interval: The distance between the peaks of two consecutive R-waves on the ECG strip at the bottom of the diagram.
• End-Diastole to End-Diastole: The time from the beginning of one ventricular contraction to the next.
• P-P Interval: The time between two consecutive P-waves.

The Calculation Formula

Since there are 60 seconds in a minute, the formula to find Heart Rate (Beats Per Minute) is:

Heart Rate (BPM) = 60 / Cardiac Cycle Duration (in seconds)

If the diagram provides the time in milliseconds (ms), use this variation:

Heart Rate (BPM) = 60,000 / Cardiac Cycle Duration (in ms)

Realistic Example

Suppose you are analyzing a Wiggers diagram where the X-axis shows that one full cardiac cycle (from the start of atrial systole to the end of ventricular diastole) takes exactly 0.75 seconds.

Using the formula:
60 / 0.75 = 80 BPM

This result indicates a normal resting heart rate. If the cycle duration was shorter (e.g., 0.5 seconds), the heart rate would increase (120 BPM), indicating physiological stress or exercise during the recording of that diagram.

Key Components of the Wiggers Diagram

While the time axis gives you the heart rate, the vertical components tell you about the heart's health:

• Ventricular Pressure: Rises sharply during isovolumetric contraction and ejection.
• Aortic Pressure: Shows the dicrotic notch when the aortic valve closes.
• Ventricular Volume: Reaches its peak at the End-Diastolic Volume (EDV) and its minimum at the End-Systolic Volume (ESV).